Trace the architectural genealogy of many of western civilization's historic buildings and you reach ancient Rome. For two millennia, revived Roman classicism in one guise or another has repeatedly informed the design of religious and government edifices, theaters and arenas, grand palaces and modest homes.

America enthusiastically absorbed the DNA of European classicism, which is evident in many of our most venerated civic and domestic buildings: Thomas Jefferson's Monticello, Virginia State Capitol and University of Virginia; dozens of other state capitols; the White House; and the U.S. Capitol building.

Why has Roman classicism been so pervasive for 2,000 years? And why, during the past two centuries, did many European and American architects rebel against classicism's aesthetic dominance and stylistic constraints? In the rejection of classicism, has something been lost?

Some answers to these questions can be found at the National Building Museum's exhibition "Palladio and His Legacy: A Transatlantic Journey." Displaying original drawings, models, treatises and pattern books, the exhibition explains how the work of Italian Renaissance architect Andrea Palladio (1508-1580), considered the Western world's most influential architect, enabled design based on Roman classicism to become the ideal, normative way to make buildings.

Palladio's lasting influence resulted from his being in the right place at the right time - along with his extraordinary talent, ambition and energy. He lived and worked in Italy during the 16th century, when Renaissance intellectual ferment was at its peak. The architectural legacy of ancient Rome was being uncovered, documented, analyzed and extolled for ideals of beauty - symmetry, proportion, harmony of elements - unappreciated during the Middle Ages.

Palladio visited, studied and made drawings of antique Roman structures. At the same time, he designed aesthetically original buildings - villas, palazzi, churches - in the Veneto, the region around Venice - the Villa Rotonda in Vicenza among the most famous. His inventive, unprecedented architectural work showed how the grammar and vocabulary of Roman classicism, a veritable kit of parts, could be applied creatively to any building.

In 1570, at the age of 62, Palladio took the step that cemented his reputation and influence for hundreds of years. He published "The Four Books on Architecture," his treatise showing what one needed to know to design beautiful, classically styled buildings. The comprehensive treatise was an architectural handbook and historic reference, but it was also a very effective marketing tool.

Palladio enjoyed a monopoly, since no other comparably practical treatise on architectural design existed at the time. Book 1 presented the theory of Roman classicism, its compositional principles and components, such as Doric, Ionic and Corinthian column orders. Books 3 and 4 contained drawings of Roman archeological antecedents. But Book 2 was Palladio's business brochure, a portfolio presenting drawings of his own exceptional work.

The treatise became a Renaissance hit. Palladio's creative designs and built work were much admired and often replicated, as was the treatise, with French and English versions published and widely disseminated in the 18th century. Palladianism was embraced wholeheartedly in England, and from there in America, especially by Jefferson. Palladian-inspired pattern books appeared and were used by builders and property owners to design new projects.

Which is precisely why some 19th- and many 20th-century architects turned away from Palladio and the language of classicism. They considered it too formulaic, too dogmatic, too unoriginal. They had tired of repetitive formal ideas and imagery that, in their view, belonged to and should remain in the past.

Modernists viewed traditionally styled architecture as aesthetically and technologically inappropriate for an era being transformed by life-changing scientific discoveries and inventions, by engineering and industrialization. Classicism was a language of stone and masonry, while modernism could employ new materials and systems of construction for often unprecedented building types. Aware of nontraditional movements in the other arts, especially painting and sculpture, modernist architects also wanted the freedom to explore new, more abstractly expressive ways to shape buildings.

However, in rejecting classicism, some architects unfortunately threw away or ignored "classic" compositional ideas that are timeless and not dependent on use of classicism's kit of parts. Neither traditional nor modern, these ideas are inherent in visual arts as well as architecture. They include symmetry and asymmetry; axiality and centrality; rhythm and repetition; proportionality; hierarchy; solid/void; and layering. Although characteristic of Greek, Roman and Palladian architecture, these compositional attributes can be present in any building, no matter what its style or when it was built.

With these classic attributes in mind, look at Washington's best modern architecture. You won't see classical styling or motifs such as domes and vaults, arches and keystones, pediments and entablatures, Roman pilasters and columns. But you will see designs embodying classic compositional ideas.

Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.

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